1 /* libthread_db assisted debugging support, generic parts.
3 Copyright (C) 1999-2018 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
22 #include "gdb_proc_service.h"
23 #include "nat/gdb_thread_db.h"
28 #include "gdbthread.h"
36 #include "solib-svr4.h"
38 #include "observable.h"
39 #include "linux-nat.h"
40 #include "nat/linux-procfs.h"
41 #include "nat/linux-ptrace.h"
42 #include "nat/linux-osdata.h"
43 #include "auto-load.h"
44 #include "cli/cli-utils.h"
47 #include "nat/linux-namespaces.h"
49 #include "common/pathstuff.h"
51 /* GNU/Linux libthread_db support.
53 libthread_db is a library, provided along with libpthread.so, which
54 exposes the internals of the thread library to a debugger. It
55 allows GDB to find existing threads, new threads as they are
56 created, thread IDs (usually, the result of pthread_self), and
57 thread-local variables.
59 The libthread_db interface originates on Solaris, where it is both
60 more powerful and more complicated. This implementation only works
61 for NPTL, the glibc threading library. It assumes that each thread
62 is permanently assigned to a single light-weight process (LWP). At
63 some point it also supported the older LinuxThreads library, but it
66 libthread_db-specific information is stored in the "private" field
67 of struct thread_info. When the field is NULL we do not yet have
68 information about the new thread; this could be temporary (created,
69 but the thread library's data structures do not reflect it yet)
70 or permanent (created using clone instead of pthread_create).
72 Process IDs managed by linux-thread-db.c match those used by
73 linux-nat.c: a common PID for all processes, an LWP ID for each
74 thread, and no TID. We save the TID in private. Keeping it out
75 of the ptid_t prevents thread IDs changing when libpthread is
76 loaded or unloaded. */
78 static const target_info thread_db_target_info
= {
80 N_("multi-threaded child process."),
81 N_("Threads and pthreads support.")
84 class thread_db_target final
: public target_ops
89 const target_info
&info () const override
90 { return thread_db_target_info
; }
92 void detach (inferior
*, int) override
;
93 ptid_t
wait (ptid_t
, struct target_waitstatus
*, int) override
;
94 void resume (ptid_t
, int, enum gdb_signal
) override
;
95 void mourn_inferior () override
;
96 void update_thread_list () override
;
97 const char *pid_to_str (ptid_t
) override
;
98 CORE_ADDR
get_thread_local_address (ptid_t ptid
,
99 CORE_ADDR load_module_addr
,
100 CORE_ADDR offset
) override
;
101 const char *extra_thread_info (struct thread_info
*) override
;
102 ptid_t
get_ada_task_ptid (long lwp
, long thread
) override
;
104 thread_info
*thread_handle_to_thread_info (const gdb_byte
*thread_handle
,
106 inferior
*inf
) override
;
109 thread_db_target::thread_db_target ()
111 this->to_stratum
= thread_stratum
;
114 static char *libthread_db_search_path
;
116 /* Set to non-zero if thread_db auto-loading is enabled
117 by the "set auto-load libthread-db" command. */
118 static int auto_load_thread_db
= 1;
120 /* "show" command for the auto_load_thread_db configuration variable. */
123 show_auto_load_thread_db (struct ui_file
*file
, int from_tty
,
124 struct cmd_list_element
*c
, const char *value
)
126 fprintf_filtered (file
, _("Auto-loading of inferior specific libthread_db "
132 set_libthread_db_search_path (const char *ignored
, int from_tty
,
133 struct cmd_list_element
*c
)
135 if (*libthread_db_search_path
== '\0')
137 xfree (libthread_db_search_path
);
138 libthread_db_search_path
= xstrdup (LIBTHREAD_DB_SEARCH_PATH
);
142 /* If non-zero, print details of libthread_db processing. */
144 static unsigned int libthread_db_debug
;
147 show_libthread_db_debug (struct ui_file
*file
, int from_tty
,
148 struct cmd_list_element
*c
, const char *value
)
150 fprintf_filtered (file
, _("libthread-db debugging is %s.\n"), value
);
153 /* If we're running on GNU/Linux, we must explicitly attach to any new
156 /* This module's target vector. */
157 static thread_db_target the_thread_db_target
;
159 /* Non-zero if we have determined the signals used by the threads
161 static int thread_signals
;
162 static sigset_t thread_stop_set
;
163 static sigset_t thread_print_set
;
165 struct thread_db_info
167 struct thread_db_info
*next
;
169 /* Process id this object refers to. */
172 /* Handle from dlopen for libthread_db.so. */
175 /* Absolute pathname from gdb_realpath to disk file used for dlopen-ing
176 HANDLE. It may be NULL for system library. */
179 /* Structure that identifies the child process for the
180 <proc_service.h> interface. */
181 struct ps_prochandle proc_handle
;
183 /* Connection to the libthread_db library. */
184 td_thragent_t
*thread_agent
;
186 /* True if we need to apply the workaround for glibc/BZ5983. When
187 we catch a PTRACE_O_TRACEFORK, and go query the child's thread
188 list, nptl_db returns the parent's threads in addition to the new
189 (single) child thread. If this flag is set, we do extra work to
190 be able to ignore such stale entries. */
191 int need_stale_parent_threads_check
;
193 /* Pointers to the libthread_db functions. */
195 td_init_ftype
*td_init_p
;
196 td_ta_new_ftype
*td_ta_new_p
;
197 td_ta_map_lwp2thr_ftype
*td_ta_map_lwp2thr_p
;
198 td_ta_thr_iter_ftype
*td_ta_thr_iter_p
;
199 td_thr_get_info_ftype
*td_thr_get_info_p
;
200 td_thr_tls_get_addr_ftype
*td_thr_tls_get_addr_p
;
201 td_thr_tlsbase_ftype
*td_thr_tlsbase_p
;
204 /* List of known processes using thread_db, and the required
206 struct thread_db_info
*thread_db_list
;
208 static void thread_db_find_new_threads_1 (ptid_t ptid
);
209 static void thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
);
211 static void check_thread_signals (void);
213 static struct thread_info
*record_thread
214 (struct thread_db_info
*info
, struct thread_info
*tp
,
215 ptid_t ptid
, const td_thrhandle_t
*th_p
, const td_thrinfo_t
*ti_p
);
217 /* Add the current inferior to the list of processes using libpthread.
218 Return a pointer to the newly allocated object that was added to
219 THREAD_DB_LIST. HANDLE is the handle returned by dlopen'ing
222 static struct thread_db_info
*
223 add_thread_db_info (void *handle
)
225 struct thread_db_info
*info
= XCNEW (struct thread_db_info
);
227 info
->pid
= ptid_get_pid (inferior_ptid
);
228 info
->handle
= handle
;
230 /* The workaround works by reading from /proc/pid/status, so it is
231 disabled for core files. */
232 if (target_has_execution
)
233 info
->need_stale_parent_threads_check
= 1;
235 info
->next
= thread_db_list
;
236 thread_db_list
= info
;
241 /* Return the thread_db_info object representing the bookkeeping
242 related to process PID, if any; NULL otherwise. */
244 static struct thread_db_info
*
245 get_thread_db_info (int pid
)
247 struct thread_db_info
*info
;
249 for (info
= thread_db_list
; info
; info
= info
->next
)
250 if (pid
== info
->pid
)
256 /* When PID has exited or has been detached, we no longer want to keep
257 track of it as using libpthread. Call this function to discard
258 thread_db related info related to PID. Note that this closes
259 LIBTHREAD_DB_SO's dlopen'ed handle. */
262 delete_thread_db_info (int pid
)
264 struct thread_db_info
*info
, *info_prev
;
268 for (info
= thread_db_list
; info
; info_prev
= info
, info
= info
->next
)
269 if (pid
== info
->pid
)
275 if (info
->handle
!= NULL
)
276 dlclose (info
->handle
);
278 xfree (info
->filename
);
281 info_prev
->next
= info
->next
;
283 thread_db_list
= info
->next
;
288 /* Use "struct private_thread_info" to cache thread state. This is
289 a substantial optimization. */
291 struct thread_db_thread_info
: public private_thread_info
293 /* Flag set when we see a TD_DEATH event for this thread. */
296 /* Cached thread state. */
297 td_thrhandle_t th
{};
301 static thread_db_thread_info
*
302 get_thread_db_thread_info (thread_info
*thread
)
304 return static_cast<thread_db_thread_info
*> (thread
->priv
.get ());
308 thread_db_err_str (td_err_e err
)
315 return "generic 'call succeeded'";
317 return "generic error";
319 return "no thread to satisfy query";
321 return "no sync handle to satisfy query";
323 return "no LWP to satisfy query";
325 return "invalid process handle";
327 return "invalid thread handle";
329 return "invalid synchronization handle";
331 return "invalid thread agent";
333 return "invalid key";
335 return "no event message for getmsg";
337 return "FPU register set not available";
339 return "application not linked with libthread";
341 return "requested event is not supported";
343 return "capability not available";
345 return "debugger service failed";
347 return "operation not applicable to";
349 return "no thread-specific data for this thread";
351 return "malloc failed";
353 return "only part of register set was written/read";
355 return "X register set not available for this thread";
356 #ifdef THREAD_DB_HAS_TD_NOTALLOC
358 return "thread has not yet allocated TLS for given module";
360 #ifdef THREAD_DB_HAS_TD_VERSION
362 return "versions of libpthread and libthread_db do not match";
364 #ifdef THREAD_DB_HAS_TD_NOTLS
366 return "there is no TLS segment in the given module";
369 snprintf (buf
, sizeof (buf
), "unknown thread_db error '%d'", err
);
374 /* Fetch the user-level thread id of PTID. */
376 static struct thread_info
*
377 thread_from_lwp (ptid_t ptid
)
382 struct thread_db_info
*info
;
383 struct thread_info
*tp
;
385 /* Just in case td_ta_map_lwp2thr doesn't initialize it completely. */
388 /* This ptid comes from linux-nat.c, which should always fill in the
390 gdb_assert (ptid_get_lwp (ptid
) != 0);
392 info
= get_thread_db_info (ptid_get_pid (ptid
));
394 /* Access an lwp we know is stopped. */
395 info
->proc_handle
.ptid
= ptid
;
396 err
= info
->td_ta_map_lwp2thr_p (info
->thread_agent
, ptid_get_lwp (ptid
),
399 error (_("Cannot find user-level thread for LWP %ld: %s"),
400 ptid_get_lwp (ptid
), thread_db_err_str (err
));
402 err
= info
->td_thr_get_info_p (&th
, &ti
);
404 error (_("thread_get_info_callback: cannot get thread info: %s"),
405 thread_db_err_str (err
));
407 /* Fill the cache. */
408 tp
= find_thread_ptid (ptid
);
409 return record_thread (info
, tp
, ptid
, &th
, &ti
);
413 /* See linux-nat.h. */
416 thread_db_notice_clone (ptid_t parent
, ptid_t child
)
418 struct thread_db_info
*info
;
420 info
= get_thread_db_info (ptid_get_pid (child
));
425 thread_from_lwp (child
);
427 /* If we do not know about the main thread yet, this would be a good
429 thread_from_lwp (parent
);
434 verbose_dlsym (void *handle
, const char *name
)
436 void *sym
= dlsym (handle
, name
);
438 warning (_("Symbol \"%s\" not found in libthread_db: %s"),
443 /* Verify inferior's '\0'-terminated symbol VER_SYMBOL starts with "%d.%d" and
444 return 1 if this version is lower (and not equal) to
445 VER_MAJOR_MIN.VER_MINOR_MIN. Return 0 in all other cases. */
448 inferior_has_bug (const char *ver_symbol
, int ver_major_min
, int ver_minor_min
)
450 struct bound_minimal_symbol version_msym
;
451 CORE_ADDR version_addr
;
452 gdb::unique_xmalloc_ptr
<char> version
;
453 int err
, got
, retval
= 0;
455 version_msym
= lookup_minimal_symbol (ver_symbol
, NULL
, NULL
);
456 if (version_msym
.minsym
== NULL
)
459 version_addr
= BMSYMBOL_VALUE_ADDRESS (version_msym
);
460 got
= target_read_string (version_addr
, &version
, 32, &err
);
461 if (err
== 0 && memchr (version
.get (), 0, got
) == version
.get () + got
- 1)
465 retval
= (sscanf (version
.get (), "%d.%d", &major
, &minor
) == 2
466 && (major
< ver_major_min
467 || (major
== ver_major_min
&& minor
< ver_minor_min
)));
473 /* Similar as thread_db_find_new_threads_1, but try to silently ignore errors
476 Return 1 if the caller should abort libthread_db initialization. Return 0
480 thread_db_find_new_threads_silently (ptid_t ptid
)
485 thread_db_find_new_threads_2 (ptid
, 1);
488 CATCH (except
, RETURN_MASK_ERROR
)
490 if (libthread_db_debug
)
491 exception_fprintf (gdb_stdlog
, except
,
492 "Warning: thread_db_find_new_threads_silently: ");
494 /* There is a bug fixed between nptl 2.6.1 and 2.7 by
495 commit 7d9d8bd18906fdd17364f372b160d7ab896ce909
496 where calls to td_thr_get_info fail with TD_ERR for statically linked
497 executables if td_thr_get_info is called before glibc has initialized
500 If the nptl bug is NOT present in the inferior and still thread_db
501 reports an error return 1. It means the inferior has corrupted thread
502 list and GDB should fall back only to LWPs.
504 If the nptl bug is present in the inferior return 0 to silently ignore
505 such errors, and let gdb enumerate threads again later. In such case
506 GDB cannot properly display LWPs if the inferior thread list is
507 corrupted. For core files it does not apply, no 'later enumeration'
510 if (!target_has_execution
|| !inferior_has_bug ("nptl_version", 2, 7))
512 exception_fprintf (gdb_stderr
, except
,
513 _("Warning: couldn't activate thread debugging "
514 "using libthread_db: "));
523 /* Lookup a library in which given symbol resides.
524 Note: this is looking in GDB process, not in the inferior.
525 Returns library name, or NULL. */
528 dladdr_to_soname (const void *addr
)
532 if (dladdr (addr
, &info
) != 0)
533 return info
.dli_fname
;
537 /* Attempt to initialize dlopen()ed libthread_db, described by INFO.
539 Failure could happen if libthread_db does not have symbols we expect,
540 or when it refuses to work with the current inferior (e.g. due to
541 version mismatch between libthread_db and libpthread). */
544 try_thread_db_load_1 (struct thread_db_info
*info
)
548 /* Initialize pointers to the dynamic library functions we will use.
549 Essential functions first. */
551 #define TDB_VERBOSE_DLSYM(info, func) \
552 info->func ## _p = (func ## _ftype *) verbose_dlsym (info->handle, #func)
554 #define TDB_DLSYM(info, func) \
555 info->func ## _p = (func ## _ftype *) dlsym (info->handle, #func)
564 CHK (TDB_VERBOSE_DLSYM (info
, td_init
));
566 err
= info
->td_init_p ();
569 warning (_("Cannot initialize libthread_db: %s"),
570 thread_db_err_str (err
));
574 CHK (TDB_VERBOSE_DLSYM (info
, td_ta_new
));
576 /* Initialize the structure that identifies the child process. */
577 info
->proc_handle
.ptid
= inferior_ptid
;
579 /* Now attempt to open a connection to the thread library. */
580 err
= info
->td_ta_new_p (&info
->proc_handle
, &info
->thread_agent
);
583 if (libthread_db_debug
)
584 fprintf_unfiltered (gdb_stdlog
, _("td_ta_new failed: %s\n"),
585 thread_db_err_str (err
));
590 #ifdef THREAD_DB_HAS_TD_VERSION
593 /* The errors above are not unexpected and silently ignored:
594 they just mean we haven't found correct version of
598 warning (_("td_ta_new failed: %s"), thread_db_err_str (err
));
603 /* These are essential. */
604 CHK (TDB_VERBOSE_DLSYM (info
, td_ta_map_lwp2thr
));
605 CHK (TDB_VERBOSE_DLSYM (info
, td_thr_get_info
));
607 /* These are not essential. */
608 TDB_DLSYM (info
, td_thr_tls_get_addr
);
609 TDB_DLSYM (info
, td_thr_tlsbase
);
611 /* It's best to avoid td_ta_thr_iter if possible. That walks data
612 structures in the inferior's address space that may be corrupted,
613 or, if the target is running, may change while we walk them. If
614 there's execution (and /proc is mounted), then we're already
615 attached to all LWPs. Use thread_from_lwp, which uses
616 td_ta_map_lwp2thr instead, which does not walk the thread list.
618 td_ta_map_lwp2thr uses ps_get_thread_area, but we can't use that
619 currently on core targets, as it uses ptrace directly. */
620 if (target_has_execution
621 && linux_proc_task_list_dir_exists (ptid_get_pid (inferior_ptid
)))
622 info
->td_ta_thr_iter_p
= NULL
;
624 CHK (TDB_VERBOSE_DLSYM (info
, td_ta_thr_iter
));
626 #undef TDB_VERBOSE_DLSYM
630 if (info
->td_ta_thr_iter_p
== NULL
)
633 int pid
= ptid_get_pid (inferior_ptid
);
635 linux_stop_and_wait_all_lwps ();
638 if (ptid_get_pid (lp
->ptid
) == pid
)
639 thread_from_lwp (lp
->ptid
);
641 linux_unstop_all_lwps ();
643 else if (thread_db_find_new_threads_silently (inferior_ptid
) != 0)
645 /* Even if libthread_db initializes, if the thread list is
646 corrupted, we'd not manage to list any threads. Better reject this
647 thread_db, and fall back to at least listing LWPs. */
651 printf_unfiltered (_("[Thread debugging using libthread_db enabled]\n"));
653 if (*libthread_db_search_path
|| libthread_db_debug
)
655 struct ui_file
*file
;
658 library
= dladdr_to_soname ((const void *) *info
->td_ta_new_p
);
660 library
= LIBTHREAD_DB_SO
;
662 /* If we'd print this to gdb_stdout when debug output is
663 disabled, still print it to gdb_stdout if debug output is
664 enabled. User visible output should not depend on debug
666 file
= *libthread_db_search_path
!= '\0' ? gdb_stdout
: gdb_stdlog
;
667 fprintf_unfiltered (file
, _("Using host libthread_db library \"%s\".\n"),
671 /* The thread library was detected. Activate the thread_db target
672 if this is the first process using it. */
673 if (thread_db_list
->next
== NULL
)
674 push_target (&the_thread_db_target
);
679 /* Attempt to use LIBRARY as libthread_db. LIBRARY could be absolute,
680 relative, or just LIBTHREAD_DB. */
683 try_thread_db_load (const char *library
, int check_auto_load_safe
)
686 struct thread_db_info
*info
;
688 if (libthread_db_debug
)
689 fprintf_unfiltered (gdb_stdlog
,
690 _("Trying host libthread_db library: %s.\n"),
693 if (check_auto_load_safe
)
695 if (access (library
, R_OK
) != 0)
697 /* Do not print warnings by file_is_auto_load_safe if the library does
698 not exist at this place. */
699 if (libthread_db_debug
)
700 fprintf_unfiltered (gdb_stdlog
, _("open failed: %s.\n"),
701 safe_strerror (errno
));
705 if (!file_is_auto_load_safe (library
, _("auto-load: Loading libthread-db "
706 "library \"%s\" from explicit "
712 handle
= dlopen (library
, RTLD_NOW
);
715 if (libthread_db_debug
)
716 fprintf_unfiltered (gdb_stdlog
, _("dlopen failed: %s.\n"), dlerror ());
720 if (libthread_db_debug
&& strchr (library
, '/') == NULL
)
724 td_init
= dlsym (handle
, "td_init");
727 const char *const libpath
= dladdr_to_soname (td_init
);
730 fprintf_unfiltered (gdb_stdlog
, _("Host %s resolved to: %s.\n"),
735 info
= add_thread_db_info (handle
);
737 /* Do not save system library name, that one is always trusted. */
738 if (strchr (library
, '/') != NULL
)
739 info
->filename
= gdb_realpath (library
).release ();
741 if (try_thread_db_load_1 (info
))
744 /* This library "refused" to work on current inferior. */
745 delete_thread_db_info (ptid_get_pid (inferior_ptid
));
749 /* Subroutine of try_thread_db_load_from_pdir to simplify it.
750 Try loading libthread_db in directory(OBJ)/SUBDIR.
751 SUBDIR may be NULL. It may also be something like "../lib64".
752 The result is true for success. */
755 try_thread_db_load_from_pdir_1 (struct objfile
*obj
, const char *subdir
)
757 const char *obj_name
= objfile_name (obj
);
759 if (obj_name
[0] != '/')
761 warning (_("Expected absolute pathname for libpthread in the"
762 " inferior, but got %s."), obj_name
);
766 std::string path
= obj_name
;
767 size_t cp
= path
.rfind ('/');
768 /* This should at minimum hit the first character. */
769 gdb_assert (cp
!= std::string::npos
);
770 path
.resize (cp
+ 1);
772 path
= path
+ subdir
+ "/";
773 path
+= LIBTHREAD_DB_SO
;
775 return try_thread_db_load (path
.c_str (), 1);
778 /* Handle $pdir in libthread-db-search-path.
779 Look for libthread_db in directory(libpthread)/SUBDIR.
780 SUBDIR may be NULL. It may also be something like "../lib64".
781 The result is true for success. */
784 try_thread_db_load_from_pdir (const char *subdir
)
788 if (!auto_load_thread_db
)
792 if (libpthread_name_p (objfile_name (obj
)))
794 if (try_thread_db_load_from_pdir_1 (obj
, subdir
))
797 /* We may have found the separate-debug-info version of
798 libpthread, and it may live in a directory without a matching
800 if (obj
->separate_debug_objfile_backlink
!= NULL
)
801 return try_thread_db_load_from_pdir_1 (obj
->separate_debug_objfile_backlink
,
810 /* Handle $sdir in libthread-db-search-path.
811 Look for libthread_db in the system dirs, or wherever a plain
812 dlopen(file_without_path) will look.
813 The result is true for success. */
816 try_thread_db_load_from_sdir (void)
818 return try_thread_db_load (LIBTHREAD_DB_SO
, 0);
821 /* Try to load libthread_db from directory DIR of length DIR_LEN.
822 The result is true for success. */
825 try_thread_db_load_from_dir (const char *dir
, size_t dir_len
)
827 if (!auto_load_thread_db
)
830 std::string path
= std::string (dir
, dir_len
) + "/" + LIBTHREAD_DB_SO
;
832 return try_thread_db_load (path
.c_str (), 1);
835 /* Search libthread_db_search_path for libthread_db which "agrees"
836 to work on current inferior.
837 The result is true for success. */
840 thread_db_load_search (void)
844 std::vector
<gdb::unique_xmalloc_ptr
<char>> dir_vec
845 = dirnames_to_char_ptr_vec (libthread_db_search_path
);
847 for (const gdb::unique_xmalloc_ptr
<char> &this_dir_up
: dir_vec
)
849 const char *this_dir
= this_dir_up
.get ();
850 const int pdir_len
= sizeof ("$pdir") - 1;
853 this_dir_len
= strlen (this_dir
);
855 if (strncmp (this_dir
, "$pdir", pdir_len
) == 0
856 && (this_dir
[pdir_len
] == '\0'
857 || this_dir
[pdir_len
] == '/'))
859 const char *subdir
= NULL
;
861 std::string subdir_holder
;
862 if (this_dir
[pdir_len
] == '/')
864 subdir_holder
= std::string (this_dir
+ pdir_len
+ 1);
865 subdir
= subdir_holder
.c_str ();
867 rc
= try_thread_db_load_from_pdir (subdir
);
871 else if (strcmp (this_dir
, "$sdir") == 0)
873 if (try_thread_db_load_from_sdir ())
881 if (try_thread_db_load_from_dir (this_dir
, this_dir_len
))
889 if (libthread_db_debug
)
890 fprintf_unfiltered (gdb_stdlog
,
891 _("thread_db_load_search returning %d\n"), rc
);
895 /* Return non-zero if the inferior has a libpthread. */
898 has_libpthread (void)
903 if (libpthread_name_p (objfile_name (obj
)))
909 /* Attempt to load and initialize libthread_db.
910 Return 1 on success. */
913 thread_db_load (void)
915 struct thread_db_info
*info
;
917 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
922 /* Don't attempt to use thread_db on executables not running
924 if (!target_has_registers
)
927 /* Don't attempt to use thread_db for remote targets. */
928 if (!(target_can_run () || core_bfd
))
931 if (thread_db_load_search ())
934 /* We couldn't find a libthread_db.
935 If the inferior has a libpthread warn the user. */
936 if (has_libpthread ())
938 warning (_("Unable to find libthread_db matching inferior's thread"
939 " library, thread debugging will not be available."));
943 /* Either this executable isn't using libpthread at all, or it is
944 statically linked. Since we can't easily distinguish these two cases,
945 no warning is issued. */
950 check_thread_signals (void)
957 lin_thread_get_thread_signals (&mask
);
958 sigemptyset (&thread_stop_set
);
959 sigemptyset (&thread_print_set
);
961 for (i
= 1; i
< NSIG
; i
++)
963 if (sigismember (&mask
, i
))
965 if (signal_stop_update (gdb_signal_from_host (i
), 0))
966 sigaddset (&thread_stop_set
, i
);
967 if (signal_print_update (gdb_signal_from_host (i
), 0))
968 sigaddset (&thread_print_set
, i
);
975 /* Check whether thread_db is usable. This function is called when
976 an inferior is created (or otherwise acquired, e.g. attached to)
977 and when new shared libraries are loaded into a running process. */
980 check_for_thread_db (void)
982 /* Do nothing if we couldn't load libthread_db.so.1. */
983 if (!thread_db_load ())
987 /* This function is called via the new_objfile observer. */
990 thread_db_new_objfile (struct objfile
*objfile
)
992 /* This observer must always be called with inferior_ptid set
996 /* libpthread with separate debug info has its debug info file already
997 loaded (and notified without successful thread_db initialization)
998 the time gdb::observers::new_objfile.notify is called for the library itself.
999 Static executables have their separate debug info loaded already
1000 before the inferior has started. */
1001 && objfile
->separate_debug_objfile_backlink
== NULL
1002 /* Only check for thread_db if we loaded libpthread,
1003 or if this is the main symbol file.
1004 We need to check OBJF_MAINLINE to handle the case of debugging
1005 a statically linked executable AND the symbol file is specified AFTER
1006 the exec file is loaded (e.g., gdb -c core ; file foo).
1007 For dynamically linked executables, libpthread can be near the end
1008 of the list of shared libraries to load, and in an app of several
1009 thousand shared libraries, this can otherwise be painful. */
1010 && ((objfile
->flags
& OBJF_MAINLINE
) != 0
1011 || libpthread_name_p (objfile_name (objfile
))))
1012 check_for_thread_db ();
1016 check_pid_namespace_match (void)
1018 /* Check is only relevant for local targets targets. */
1019 if (target_can_run ())
1021 /* If the child is in a different PID namespace, its idea of its
1022 PID will differ from our idea of its PID. When we scan the
1023 child's thread list, we'll mistakenly think it has no threads
1024 since the thread PID fields won't match the PID we give to
1026 if (!linux_ns_same (ptid_get_pid (inferior_ptid
), LINUX_NS_PID
))
1028 warning (_ ("Target and debugger are in different PID "
1029 "namespaces; thread lists and other data are "
1030 "likely unreliable. "
1031 "Connect to gdbserver inside the container."));
1036 /* This function is called via the inferior_created observer.
1037 This handles the case of debugging statically linked executables. */
1040 thread_db_inferior_created (struct target_ops
*target
, int from_tty
)
1042 check_pid_namespace_match ();
1043 check_for_thread_db ();
1046 /* Update the thread's state (what's displayed in "info threads"),
1047 from libthread_db thread state information. */
1050 update_thread_state (thread_db_thread_info
*priv
,
1051 const td_thrinfo_t
*ti_p
)
1053 priv
->dying
= (ti_p
->ti_state
== TD_THR_UNKNOWN
1054 || ti_p
->ti_state
== TD_THR_ZOMBIE
);
1057 /* Record a new thread in GDB's thread list. Creates the thread's
1058 private info. If TP is NULL or TP is marked as having exited,
1059 creates a new thread. Otherwise, uses TP. */
1061 static struct thread_info
*
1062 record_thread (struct thread_db_info
*info
,
1063 struct thread_info
*tp
,
1064 ptid_t ptid
, const td_thrhandle_t
*th_p
,
1065 const td_thrinfo_t
*ti_p
)
1067 /* A thread ID of zero may mean the thread library has not
1068 initialized yet. Leave private == NULL until the thread library
1070 if (ti_p
->ti_tid
== 0)
1073 /* Construct the thread's private data. */
1074 thread_db_thread_info
*priv
= new thread_db_thread_info
;
1077 priv
->tid
= ti_p
->ti_tid
;
1078 update_thread_state (priv
, ti_p
);
1080 /* Add the thread to GDB's thread list. If we already know about a
1081 thread with this PTID, but it's marked exited, then the kernel
1082 reused the tid of an old thread. */
1083 if (tp
== NULL
|| tp
->state
== THREAD_EXITED
)
1084 tp
= add_thread_with_info (ptid
, priv
);
1086 tp
->priv
.reset (priv
);
1088 if (target_has_execution
)
1089 check_thread_signals ();
1095 thread_db_target::detach (inferior
*inf
, int from_tty
)
1097 struct target_ops
*target_beneath
= find_target_beneath (this);
1099 delete_thread_db_info (inf
->pid
);
1101 target_beneath
->detach (inf
, from_tty
);
1103 /* NOTE: From this point on, inferior_ptid is null_ptid. */
1105 /* If there are no more processes using libpthread, detach the
1106 thread_db target ops. */
1107 if (!thread_db_list
)
1108 unpush_target (this);
1112 thread_db_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
1115 struct thread_db_info
*info
;
1116 struct target_ops
*beneath
= find_target_beneath (this);
1118 ptid
= beneath
->wait (ptid
, ourstatus
, options
);
1120 switch (ourstatus
->kind
)
1122 case TARGET_WAITKIND_IGNORE
:
1123 case TARGET_WAITKIND_EXITED
:
1124 case TARGET_WAITKIND_THREAD_EXITED
:
1125 case TARGET_WAITKIND_SIGNALLED
:
1129 info
= get_thread_db_info (ptid_get_pid (ptid
));
1131 /* If this process isn't using thread_db, we're done. */
1135 if (ourstatus
->kind
== TARGET_WAITKIND_EXECD
)
1137 /* New image, it may or may not end up using thread_db. Assume
1138 not unless we find otherwise. */
1139 delete_thread_db_info (ptid_get_pid (ptid
));
1140 if (!thread_db_list
)
1141 unpush_target (&the_thread_db_target
);
1146 /* Fill in the thread's user-level thread id and status. */
1147 thread_from_lwp (ptid
);
1153 thread_db_target::mourn_inferior ()
1155 struct target_ops
*target_beneath
= find_target_beneath (this);
1157 delete_thread_db_info (ptid_get_pid (inferior_ptid
));
1159 target_beneath
->mourn_inferior ();
1161 /* Detach thread_db target ops. */
1162 if (!thread_db_list
)
1163 unpush_target (&the_thread_db_target
);
1166 struct callback_data
1168 struct thread_db_info
*info
;
1173 find_new_threads_callback (const td_thrhandle_t
*th_p
, void *data
)
1178 struct thread_info
*tp
;
1179 struct callback_data
*cb_data
= (struct callback_data
*) data
;
1180 struct thread_db_info
*info
= cb_data
->info
;
1182 err
= info
->td_thr_get_info_p (th_p
, &ti
);
1184 error (_("find_new_threads_callback: cannot get thread info: %s"),
1185 thread_db_err_str (err
));
1187 if (ti
.ti_lid
== -1)
1189 /* A thread with kernel thread ID -1 is either a thread that
1190 exited and was joined, or a thread that is being created but
1191 hasn't started yet, and that is reusing the tcb/stack of a
1192 thread that previously exited and was joined. (glibc marks
1193 terminated and joined threads with kernel thread ID -1. See
1195 if (libthread_db_debug
)
1196 fprintf_unfiltered (gdb_stdlog
,
1197 "thread_db: skipping exited and "
1198 "joined thread (0x%lx)\n",
1199 (unsigned long) ti
.ti_tid
);
1205 /* A thread ID of zero means that this is the main thread, but
1206 glibc has not yet initialized thread-local storage and the
1207 pthread library. We do not know what the thread's TID will
1210 /* In that case, we're not stopped in a fork syscall and don't
1211 need this glibc bug workaround. */
1212 info
->need_stale_parent_threads_check
= 0;
1217 /* Ignore stale parent threads, caused by glibc/BZ5983. This is a
1218 bit expensive, as it needs to open /proc/pid/status, so try to
1219 avoid doing the work if we know we don't have to. */
1220 if (info
->need_stale_parent_threads_check
)
1222 int tgid
= linux_proc_get_tgid (ti
.ti_lid
);
1224 if (tgid
!= -1 && tgid
!= info
->pid
)
1228 ptid
= ptid_build (info
->pid
, ti
.ti_lid
, 0);
1229 tp
= find_thread_ptid (ptid
);
1230 if (tp
== NULL
|| tp
->priv
== NULL
)
1231 record_thread (info
, tp
, ptid
, th_p
, &ti
);
1236 /* Helper for thread_db_find_new_threads_2.
1237 Returns number of new threads found. */
1240 find_new_threads_once (struct thread_db_info
*info
, int iteration
,
1243 struct callback_data data
;
1244 td_err_e err
= TD_ERR
;
1247 data
.new_threads
= 0;
1249 /* See comment in thread_db_update_thread_list. */
1250 gdb_assert (info
->td_ta_thr_iter_p
!= NULL
);
1254 /* Iterate over all user-space threads to discover new threads. */
1255 err
= info
->td_ta_thr_iter_p (info
->thread_agent
,
1256 find_new_threads_callback
,
1259 TD_THR_LOWEST_PRIORITY
,
1261 TD_THR_ANY_USER_FLAGS
);
1263 CATCH (except
, RETURN_MASK_ERROR
)
1265 if (libthread_db_debug
)
1267 exception_fprintf (gdb_stdlog
, except
,
1268 "Warning: find_new_threads_once: ");
1273 if (libthread_db_debug
)
1275 fprintf_unfiltered (gdb_stdlog
,
1276 _("Found %d new threads in iteration %d.\n"),
1277 data
.new_threads
, iteration
);
1283 return data
.new_threads
;
1286 /* Search for new threads, accessing memory through stopped thread
1287 PTID. If UNTIL_NO_NEW is true, repeat searching until several
1288 searches in a row do not discover any new threads. */
1291 thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
)
1293 td_err_e err
= TD_OK
;
1294 struct thread_db_info
*info
;
1297 info
= get_thread_db_info (ptid_get_pid (ptid
));
1299 /* Access an lwp we know is stopped. */
1300 info
->proc_handle
.ptid
= ptid
;
1304 /* Require 4 successive iterations which do not find any new threads.
1305 The 4 is a heuristic: there is an inherent race here, and I have
1306 seen that 2 iterations in a row are not always sufficient to
1307 "capture" all threads. */
1308 for (i
= 0, loop
= 0; loop
< 4 && err
== TD_OK
; ++i
, ++loop
)
1309 if (find_new_threads_once (info
, i
, &err
) != 0)
1311 /* Found some new threads. Restart the loop from beginning. */
1316 find_new_threads_once (info
, 0, &err
);
1319 error (_("Cannot find new threads: %s"), thread_db_err_str (err
));
1323 thread_db_find_new_threads_1 (ptid_t ptid
)
1325 thread_db_find_new_threads_2 (ptid
, 0);
1328 /* Implement the to_update_thread_list target method for this
1332 thread_db_target::update_thread_list ()
1334 struct thread_db_info
*info
;
1335 struct inferior
*inf
;
1341 struct thread_info
*thread
;
1346 info
= get_thread_db_info (inf
->pid
);
1350 thread
= any_live_thread_of_process (inf
->pid
);
1351 if (thread
== NULL
|| thread
->executing
)
1354 /* It's best to avoid td_ta_thr_iter if possible. That walks
1355 data structures in the inferior's address space that may be
1356 corrupted, or, if the target is running, the list may change
1357 while we walk it. In the latter case, it's possible that a
1358 thread exits just at the exact time that causes GDB to get
1359 stuck in an infinite loop. To avoid pausing all threads
1360 whenever the core wants to refresh the thread list, we
1361 instead use thread_from_lwp immediately when we see an LWP
1362 stop. That uses thread_db entry points that do not walk
1363 libpthread's thread list, so should be safe, as well as more
1365 if (target_has_execution_1 (thread
->ptid
))
1368 thread_db_find_new_threads_1 (thread
->ptid
);
1371 /* Give the beneath target a chance to do extra processing. */
1372 this->beneath
->update_thread_list ();
1376 thread_db_target::pid_to_str (ptid_t ptid
)
1378 struct thread_info
*thread_info
= find_thread_ptid (ptid
);
1379 struct target_ops
*beneath
;
1381 if (thread_info
!= NULL
&& thread_info
->priv
!= NULL
)
1383 static char buf
[64];
1384 thread_db_thread_info
*priv
= get_thread_db_thread_info (thread_info
);
1386 snprintf (buf
, sizeof (buf
), "Thread 0x%lx (LWP %ld)",
1387 (unsigned long) priv
->tid
, ptid_get_lwp (ptid
));
1392 beneath
= find_target_beneath (this);
1393 return beneath
->pid_to_str (ptid
);
1396 /* Return a string describing the state of the thread specified by
1400 thread_db_target::extra_thread_info (thread_info
*info
)
1402 if (info
->priv
== NULL
)
1405 thread_db_thread_info
*priv
= get_thread_db_thread_info (info
);
1413 /* Return pointer to the thread_info struct which corresponds to
1414 THREAD_HANDLE (having length HANDLE_LEN). */
1417 thread_db_target::thread_handle_to_thread_info (const gdb_byte
*thread_handle
,
1421 struct thread_info
*tp
;
1422 thread_t handle_tid
;
1424 /* Thread handle sizes must match in order to proceed. We don't use an
1425 assert here because the resulting internal error will cause GDB to
1426 exit. This isn't necessarily an internal error due to the possibility
1427 of garbage being passed as the thread handle via the python interface. */
1428 if (handle_len
!= sizeof (handle_tid
))
1429 error (_("Thread handle size mismatch: %d vs %zu (from libthread_db)"),
1430 handle_len
, sizeof (handle_tid
));
1432 handle_tid
= * (const thread_t
*) thread_handle
;
1434 ALL_NON_EXITED_THREADS (tp
)
1436 thread_db_thread_info
*priv
= get_thread_db_thread_info (tp
);
1438 if (tp
->inf
== inf
&& priv
!= NULL
&& handle_tid
== priv
->tid
)
1445 /* Get the address of the thread local variable in load module LM which
1446 is stored at OFFSET within the thread local storage for thread PTID. */
1449 thread_db_target::get_thread_local_address (ptid_t ptid
,
1453 struct thread_info
*thread_info
;
1454 struct target_ops
*beneath
;
1456 /* Find the matching thread. */
1457 thread_info
= find_thread_ptid (ptid
);
1459 /* We may not have discovered the thread yet. */
1460 if (thread_info
!= NULL
&& thread_info
->priv
== NULL
)
1461 thread_info
= thread_from_lwp (ptid
);
1463 if (thread_info
!= NULL
&& thread_info
->priv
!= NULL
)
1467 thread_db_info
*info
= get_thread_db_info (ptid_get_pid (ptid
));
1468 thread_db_thread_info
*priv
= get_thread_db_thread_info (thread_info
);
1470 /* Finally, get the address of the variable. */
1473 /* glibc doesn't provide the needed interface. */
1474 if (!info
->td_thr_tls_get_addr_p
)
1475 throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR
,
1476 _("No TLS library support"));
1478 /* Note the cast through uintptr_t: this interface only works if
1479 a target address fits in a psaddr_t, which is a host pointer.
1480 So a 32-bit debugger can not access 64-bit TLS through this. */
1481 err
= info
->td_thr_tls_get_addr_p (&priv
->th
,
1482 (psaddr_t
)(uintptr_t) lm
,
1487 /* If glibc doesn't provide the needed interface throw an error
1488 that LM is zero - normally cases it should not be. */
1489 if (!info
->td_thr_tlsbase_p
)
1490 throw_error (TLS_LOAD_MODULE_NOT_FOUND_ERROR
,
1491 _("TLS load module not found"));
1493 /* This code path handles the case of -static -pthread executables:
1494 https://sourceware.org/ml/libc-help/2014-03/msg00024.html
1495 For older GNU libc r_debug.r_map is NULL. For GNU libc after
1496 PR libc/16831 due to GDB PR threads/16954 LOAD_MODULE is also NULL.
1497 The constant number 1 depends on GNU __libc_setup_tls
1498 initialization of l_tls_modid to 1. */
1499 err
= info
->td_thr_tlsbase_p (&priv
->th
, 1, &address
);
1500 address
= (char *) address
+ offset
;
1503 #ifdef THREAD_DB_HAS_TD_NOTALLOC
1504 /* The memory hasn't been allocated, yet. */
1505 if (err
== TD_NOTALLOC
)
1506 /* Now, if libthread_db provided the initialization image's
1507 address, we *could* try to build a non-lvalue value from
1508 the initialization image. */
1509 throw_error (TLS_NOT_ALLOCATED_YET_ERROR
,
1510 _("TLS not allocated yet"));
1513 /* Something else went wrong. */
1515 throw_error (TLS_GENERIC_ERROR
,
1516 (("%s")), thread_db_err_str (err
));
1518 /* Cast assuming host == target. Joy. */
1519 /* Do proper sign extension for the target. */
1520 gdb_assert (exec_bfd
);
1521 return (bfd_get_sign_extend_vma (exec_bfd
) > 0
1522 ? (CORE_ADDR
) (intptr_t) address
1523 : (CORE_ADDR
) (uintptr_t) address
);
1526 beneath
= find_target_beneath (this);
1527 return beneath
->get_thread_local_address (ptid
, lm
, offset
);
1530 /* Implement the to_get_ada_task_ptid target method for this target. */
1533 thread_db_target::get_ada_task_ptid (long lwp
, long thread
)
1535 /* NPTL uses a 1:1 model, so the LWP id suffices. */
1536 return ptid_build (ptid_get_pid (inferior_ptid
), lwp
, 0);
1540 thread_db_target::resume (ptid_t ptid
, int step
, enum gdb_signal signo
)
1542 struct target_ops
*beneath
= find_target_beneath (this);
1543 struct thread_db_info
*info
;
1545 if (ptid_equal (ptid
, minus_one_ptid
))
1546 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
1548 info
= get_thread_db_info (ptid_get_pid (ptid
));
1550 /* This workaround is only needed for child fork lwps stopped in a
1551 PTRACE_O_TRACEFORK event. When the inferior is resumed, the
1552 workaround can be disabled. */
1554 info
->need_stale_parent_threads_check
= 0;
1556 beneath
->resume (ptid
, step
, signo
);
1559 /* std::sort helper function for info_auto_load_libthread_db, sort the
1560 thread_db_info pointers primarily by their FILENAME and secondarily by their
1561 PID, both in ascending order. */
1564 info_auto_load_libthread_db_compare (const struct thread_db_info
*a
,
1565 const struct thread_db_info
*b
)
1569 retval
= strcmp (a
->filename
, b
->filename
);
1573 return a
->pid
< b
->pid
;
1576 /* Implement 'info auto-load libthread-db'. */
1579 info_auto_load_libthread_db (const char *args
, int from_tty
)
1581 struct ui_out
*uiout
= current_uiout
;
1582 const char *cs
= args
? args
: "";
1583 struct thread_db_info
*info
;
1584 unsigned unique_filenames
;
1585 size_t max_filename_len
, pids_len
;
1588 cs
= skip_spaces (cs
);
1590 error (_("'info auto-load libthread-db' does not accept any parameters"));
1592 std::vector
<struct thread_db_info
*> array
;
1593 for (info
= thread_db_list
; info
; info
= info
->next
)
1594 if (info
->filename
!= NULL
)
1595 array
.push_back (info
);
1597 /* Sort ARRAY by filenames and PIDs. */
1598 std::sort (array
.begin (), array
.end (),
1599 info_auto_load_libthread_db_compare
);
1601 /* Calculate the number of unique filenames (rows) and the maximum string
1602 length of PIDs list for the unique filenames (columns). */
1604 unique_filenames
= 0;
1605 max_filename_len
= 0;
1607 for (i
= 0; i
< array
.size (); i
++)
1609 int pid
= array
[i
]->pid
;
1610 size_t this_pid_len
;
1612 for (this_pid_len
= 0; pid
!= 0; pid
/= 10)
1615 if (i
== 0 || strcmp (array
[i
- 1]->filename
, array
[i
]->filename
) != 0)
1618 max_filename_len
= std::max (max_filename_len
,
1619 strlen (array
[i
]->filename
));
1622 pids_len
-= strlen (", ");
1625 pids_len
+= this_pid_len
+ strlen (", ");
1628 pids_len
-= strlen (", ");
1630 /* Table header shifted right by preceding "libthread-db: " would not match
1632 if (array
.size () > 0 && args
== auto_load_info_scripts_pattern_nl
)
1636 ui_out_emit_table
table_emitter (uiout
, 2, unique_filenames
,
1637 "LinuxThreadDbTable");
1639 uiout
->table_header (max_filename_len
, ui_left
, "filename", "Filename");
1640 uiout
->table_header (pids_len
, ui_left
, "PIDs", "Pids");
1641 uiout
->table_body ();
1643 /* Note I is incremented inside the cycle, not at its end. */
1644 for (i
= 0; i
< array
.size ();)
1646 ui_out_emit_tuple
tuple_emitter (uiout
, NULL
);
1649 uiout
->field_string ("filename", info
->filename
);
1652 while (i
< array
.size () && strcmp (info
->filename
,
1653 array
[i
]->filename
) == 0)
1657 string_appendf (pids
, "%u", array
[i
]->pid
);
1661 uiout
->field_string ("pids", pids
.c_str ());
1668 uiout
->message (_("No auto-loaded libthread-db.\n"));
1672 _initialize_thread_db (void)
1674 /* Defer loading of libthread_db.so until inferior is running.
1675 This allows gdb to load correct libthread_db for a given
1676 executable -- there could be multiple versions of glibc,
1677 and until there is a running inferior, we can't tell which
1678 libthread_db is the correct one to load. */
1680 libthread_db_search_path
= xstrdup (LIBTHREAD_DB_SEARCH_PATH
);
1682 add_setshow_optional_filename_cmd ("libthread-db-search-path",
1684 &libthread_db_search_path
, _("\
1685 Set search path for libthread_db."), _("\
1686 Show the current search path or libthread_db."), _("\
1687 This path is used to search for libthread_db to be loaded into \
1689 Its value is a colon (':') separate list of directories to search.\n\
1690 Setting the search path to an empty list resets it to its default value."),
1691 set_libthread_db_search_path
,
1693 &setlist
, &showlist
);
1695 add_setshow_zuinteger_cmd ("libthread-db", class_maintenance
,
1696 &libthread_db_debug
, _("\
1697 Set libthread-db debugging."), _("\
1698 Show libthread-db debugging."), _("\
1699 When non-zero, libthread-db debugging is enabled."),
1701 show_libthread_db_debug
,
1702 &setdebuglist
, &showdebuglist
);
1704 add_setshow_boolean_cmd ("libthread-db", class_support
,
1705 &auto_load_thread_db
, _("\
1706 Enable or disable auto-loading of inferior specific libthread_db."), _("\
1707 Show whether auto-loading inferior specific libthread_db is enabled."), _("\
1708 If enabled, libthread_db will be searched in 'set libthread-db-search-path'\n\
1709 locations to load libthread_db compatible with the inferior.\n\
1710 Standard system libthread_db still gets loaded even with this option off.\n\
1711 This options has security implications for untrusted inferiors."),
1712 NULL
, show_auto_load_thread_db
,
1713 auto_load_set_cmdlist_get (),
1714 auto_load_show_cmdlist_get ());
1716 add_cmd ("libthread-db", class_info
, info_auto_load_libthread_db
,
1717 _("Print the list of loaded inferior specific libthread_db.\n\
1718 Usage: info auto-load libthread-db"),
1719 auto_load_info_cmdlist_get ());
1721 /* Add ourselves to objfile event chain. */
1722 gdb::observers::new_objfile
.attach (thread_db_new_objfile
);
1724 /* Add ourselves to inferior_created event chain.
1725 This is needed to handle debugging statically linked programs where
1726 the new_objfile observer won't get called for libpthread. */
1727 gdb::observers::inferior_created
.attach (thread_db_inferior_created
);